Session Y27: Focus Session: Kagome Magnets
11:15 AM–2:15 PM, Friday, March 14, 2008
Morial Convention Center Room: 219
Sponsoring Unit:
GMAG
Chair: Ying Chen, National Institute of Standards and Technology
Abstract ID: BAPS.2008.MAR.Y27.6
Abstract: Y27.00006 : Classical antiferromagnet on a hyper-kagome lattice
12:15 PM–12:27 PM
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Abstract 
Authors:
John Hopkinson
(Brandon University)
Sergei Isakov
(ETH-Zurich)
Hae-Young Kee
(University of Toronto)
Yong Baek Kim
(University of Toronto)
Motivated by recent experiments on Na$_4$Ir$_3$O$_8$ [Y. Okamoto {\it{et al.}}, Phys. Rev. Lett. 99, 167402 (2007)], we study the classical antiferromagnet on a frustrated three-dimensional lattice obtained by selectively removing one of four sites in each tetrahedron of the pyrochlore lattice. This ``hyper-kagome'' lattice consists of corner-sharing triangles. We present (J. Hopkinson {\it{et al.}}, Phys. Rev. Lett. 99, 037201 (2007)) the results of large-$N$ mean field theory and Monte Carlo computations on $O(N)$ classical spin models. We find the classical ground states to be highly degenerate. Nonetheless, at low temperatures, nematic order emerges via ``order by disorder'' in the Heisenberg model ($N$=3), representing the dominance of coplanar spin configurations. Above this transition, the spin-spin correlations show a dipolar form which can be understood to arise from a generalized ``Gauss' law'' constraint. The relevance of these results to ongoing neutron scattering measurements will be discussed.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2008.MAR.Y27.6